For some time, the use has been proposed, firsly in the manufacture of paper and then, recently, in rolling mills, of rolls with a rotating sleeve comprising a fixed support shaft in the form of an extended beam, surrounded by a tubular sleeve mounted so as to rotate on the beam about bearings defining an axis of rotation transverse to the rolling axis, and resting on the beam by means of a plurality of support means distributed side by side along the length of the beam and centered on an axial support plane which corresponds to the plane of transmission of the rolling stress when the roll forms part of a rolling mill. In fact, the tubular sleeve, which has a relatively thin, is deformable, and, by acting selectively on the various support means, it is possible to give the external surface of the roll, for example in a rolling mill of a quarto or sexto type, a profile making it possible to compensate for the bending of the shaft and to correct defects in the surface evenness or thickness occurring on the product during rolling.
Rolls with rotating sleeves have long been known in the paper industry and, e.g., US-A-2,395,915 describes a roll of this type in which each support member consists of a part in the shape of a stirrup which rests on the inner surface of the sleeve by means of three rollers separated by about 120.degree., or a central roller located in the contact plane passing through the axis of the rolls and two lateral rollers resting on the guiding surfaces of the support shaft and parallel to the contact plane, respectively. In this manner, the tubular sleeve is held perfectly centred in the contact plane by the various support members distributed along its entire length.
However, such a system of centering by means of rollers does not allow the transmission of considerable stresses at high rotational speeds, and it is therefore preferred to embody the adjustment of the profile of the sleeve by means of support shoes centered in the contact plane and inserted between the shaft and the sleeve, each shoe resting, on the one hand, on the inner surface of the sleeve by means of a cylindrical support surface of substantially the same radius and, on the other hand, on the support shaft by means of an adjustable thrust means, generally a hydraulic jack, which allows individual adjustment of the thrust of each shoe in the radial direction so as to give the tubular sleeve the appropriate profile.
A hydraulic fluid is introduced continuously between the support surface of the shoe and the inner surface of the sleeve so as to form a lubricating film allowing the rotation of the sleeve resting on the shoes as described, for example, in US-A-3,131,625.
In these known arrangements, the centering of the sleeve on the shaft was provided by support members distributed along its entire length, and centering bearings are not provided at the ends of the sleeve.
However, the sleeve mounted in this way, floating on the ends of the shoes, tends to become deformed and to be moved transversely by the product itself when the latter is applied directly on the roll, or, alternatively, by the rotation of the adjacent roll in the case where, for example, the roll with rotating sleeve is the support roll of a rolling mill. The tubular sleeve is then preferably held at each end by centring bearings which are themselves held centered in the contact plane. Each bearing conventionally consists of an outer ring and an inner ring between which are inserted rollers or balls, the outter ring being fixed to the sleeve and the inner ring being centered in the contact plane by means of sliding guide members arranged on the support shaft.
For example, according to an arrangement provided for this purpose in FR-A-2,083,171, the inner ring of each bearing is equipped with guide surfaces which are mounted so as to slide along a corresponding flat surface arranged on the support shaft and parallel to the contact plane. In this manner, the tubular sleeve may be moved slightly with respect to the support shaft as a function of the stresses applied, but while remaining perfectly centered in the contact plane.
These known arrangements, which were provided for the paper industry, i.e., for relatively small stresses, are not immediately applicable to the metallurgical industry and, in particular, to rolling mills in which the cylinder must transmit a very considerable rolling stress and, moreover, tends to be displaced parallel to the axis with respect to the support shaft under the influence of the stresses applied.
It is therefore necessary to provide axial support for the sleeve but to leave the latter free to position and deform itself independently of the shaft.